1. Technical Field
The object of this invention is an improvement of a bi-elastic device, particularly for the elasticizing of an ear-piece for spectacles. The innovation finds particular, if not exclusive, application in the field of spectacles production, including small metal parts and their fittings.
2. Background Art
It is known that many frames for spectacles are found in the prior art. Some of these frames have devices located close to their hinging for allowing the elastic fastening of ear-pieces to a part of the frame known as a front face. Having such a device located on both sides of the spectacles has the advantage of giving a better fit, because if the ear-pieces exert a low pressure on a person's temples, they are easier to endure by most people, and the spectacles are more adaptable to the different anatomical shapes of each subject. Therefore, the firms in this field are constantly attempting to find innovative and improved solutions, both with regard to function and size of these devices, when compared to the preexisting devices.
For example, a traditional elasticized ear-piece, that found wide acceptance among consumers is disclosed in the European patent application n.79400087.7, in which an elastic hinge was described for a spectacles frame. The elastic hinge comprises a box associated sideways to the ear-piece, the box containing a tie-rod coaxial to the box, and in which an end portion of the tie-rod is threaded, on which is screwed a bushing that ensures the positioning of a spring, while the other side of the tie-rod is in abutment on the inside of a seat in the box.
Another system, conceptually based on the solution provided by the previous patent, is disclosed in the utility model n.181221, which has an improved hinge for the articulation of a spectacles frame with an elastically openable ear-piece. A squared support is provided in the frame, on which is inserted a support which is also squared that makes up a shoulder for the compression of a spring.
Finally, the Italian Patent n. 1 147 198 discloses an ear-piece for spectacles with an elastic hinging in which an end of the ear-piece has an axially holed small block within which is inserted one end for the connection of the hinge. Continuing with a reduced diameter, it supports a sharp edge that is fixed inside the borehole while on the back of the borehole is a tension helicoidal spring blocked at an end by a threaded locknut. In such a case, it is possible for the elastic opening of the ear-piece to achieve a certain angle by an elastic yielding of the hinge-like connection.
The common drawbacks noticed in the above-mentioned solutions include excessive complexity of the utilized devices and a total oversizing of the device. Furthermore, notwithstanding that the above-mentioned devices may perform their functions perfectly, they have many problems during the manufacturing phase, such as the manufacturing of the many precision components, as well as their assembly, each considerably influencing the manufacturing time and cost. Therefore, a main purpose of the firms of the field has been to obtain elasticizing devices for ear-pieces that are smaller in size, offer good functionality while at the same time reducing the number of components, and decrease the assembly time and costs.
In the numerous recent devices on the market that are more or less effective and in line with the above mentioned principles, there is a solution in which the articulation is an ear-piece with a sliding body containing an elasticizing spring. In more detail, the body has a square cross section, in which some material has been removed longitudinally from one part of the body to another to obtain opposite thin sheets which define a guide seat, and make up containing walls of a spring. On one side, the spring is placed in abutment on the seat, while on the other, the spring is fastened to a tooth which protrudes outward with respect to the profile defined by the sliding body. Also, the device has a half-hull, is opened on one side and is associated with an ear-piece, and on the inside of the half-hull the sliding body, including the spring, is inserted. As a result, the tooth on the longitudinal surface acts as a stop reference. Being in a traction condition, the articulation causes the body to slide on the inside of the half-hull while causing the tooth to constantly grip along the base of the half-hull to compress the spring, and therefore recall elastically the articulation itself.
It is also very common to fasten to the box, preassembled, on the end of the ear-piece, an elastic yielding group consisting of an articulation on which is screwed a tie-rod coaxial to a spring and fastened on the opposite side by a suitable bushing. As a result, it is possible to notice at least two drawbacks, the need for an adequate size, which influences the weight of the structure, aesthetics not excluded, and the use of screws which involve considerable assembling time, and therefore considerable costs. For some ear-pieces, this device is considered valuable and the system is still valid, as seen by its wide use, but for the others, directed to a wider public, the device would not be any more convenient, because of the high costs of the frame. Continuous research in the field, in recent years, was therefore directed towards alternative devices, designed for being produced in a great quantities and mainly able to obviate the use of the spring passing the box for the fastening of the elastic yielding group.
It is also known that the French Patent n. 2 517 080 describes a hinge for a spectacles frame, in which a metal core is one with the articulation hinged to the front face. The core is placed, passing from one side to the other, coaxial to a box, and near one end of the box, a housing is provided that is able to contain an helicoidal compression spring. One side of the helicoidal compression spring is positioned in abutment to an annular edge obtained through a working internal to the box, and the other side of the helicoidal compression spring is positioned on the end partially inserted inside the box and which covers the end of the core. The effect obtained by opening the era-piece, consists of the coaxial sliding of the end with respect to the box containing the device. The drawbacks of this latter solution include of the fact that some complex components are still required, which make manufacturing and assembling particularly difficult, not excluding some manufacturing costs which would considerably affect the finished product.
Also in the prior art are other known improved elastic yielding devices, which are derived more or less from the previously described solutions, and which exhibit some of the problems related to the large size of the articulation.
The fact is that elasticizing devices are particularly bulky and unpleasant to see because the ear-piece shape limits and conditions the device's application. Another negative aspect commonly noticeable in the above-mentioned solutions, includes the fact that it is not possible to combine the already finished device directly with the ear-piece and instead involve rather long assembling times. Finally, the traditional ear-pieces have a tie-rod which, because of its shape, allows for excessive slack being inclined as a torsion, that is not much liked by the consumer. The purpose of this invention is to obviate the above-mentioned drawbacks.
Similar elastic hinging solutions are disclosed in DE2948113A (double spring box solution); FR2097211A (spring box solution), EP0462936A (double spring box solution); and EP0239011A (spring box solution).
In addition, FR-A-2702573 discloses a resilient hinge for a spectacle frame comprising a box (12) housing a spring (40) in abutment on the box (12) on the hinge side; the other end of the spring being in a toothed-end (31) of a L-shaped hinge element (30) inserted in the box. This solution requires a complicated mechanism consisting of: an axial guide means (42) for the spring (40); and the axial guide means (42) having a pyramidal square-head (44-45,46), abutting against a V-shaped anvil (50-58) with a tooth (52-54) that engages with a notch (14) contained in the box (12-18) that includes the respective spring (40).
A proposal of the same applicant consisted of a device, particularly reduced, for the elasticizing of an ear-piece for spectacles, comprising a small box being combined with an ear-piece by spot-welding and pre-assembly. Two springs are housed inside the box, each of the springs having one side being in abutment on the bottom of the small box and the other side being placed in abutment with an end of a tie-rod. The tie-rod is essentially "T" like and one of the two springs is placed on each side of the end of the tie-rod. The tie-rod has an opposite end that is provided with a suitable hole and is hingeable to a corresponding small front face provided on the frame of the spectacles. Another purpose of this invention is that of improving this solution in combination with the teaching of FR-A-2702573, but in which the features of the mechanism are less complicated and less expensive.